I was part of the Lost Continents TF2 community for many years around 2008-2010. There were many early season Invite guys that were part of the community, like Orzo, slardel and others. We used to play in-house Highlander a lot, and I found it pretty fun. I just kinda thought Highlander was some made up thing that someone there invented, I didn't realize it was a whole competitive mode with a league and all that. With time, we started playing HL less and playing in-house sixes (of course).
Reddit used to hold an event called the Round Robin, which was an annual event for people to come and try competitive for the first time, get mentored by dudes who knew their shit i.e. hein, and get cast by real casters like Kip. To be honest I'm not sure how I found out about it, but I had been playing the game for like 5 years, and figured it would be fun to play on a team. After that I got asked by a member of the TrashedGamers community to join her Silver HL team and I played a couple seasons in UGC. Fun times for sure. I decided I was better at talking into a microphone than playing though, so the comp career didn't last long. All I wish in hindsight is that I had found out about comp and gotten into it sooner!